We are investigating the hypothesis that some forms of retinal-choroidal degeneration are due to oxidative tissue damage caused by insufficiencies in physiological antioxidant mechanisms. The overall objective of this research is to identify nutritional factors which can help to preserve the health of the retina and retinal pigment epithelium (RPE) in old age as well as to rescue the system from disease states. Central goals are to understand the mechanisms of antioxidant function in ocular tissues as well as improve methods for maintaining the isolated components in intact form for mechanistic studies. Experimental pathology, induced by dietary deficiencies, will be used to help identify normal antioxidant factors and their functional mechanisms. Effects of dietary variables on interactions between the photoreceptor outer segments and RPE will be investigated. We also plan to study the roles of dietary antioxidants on the sensitivity of the retina-RPE to light damage. In order to better understand the dynamics of the relationship between the retina and the RPE, we plan to study the processing mechanisms by which the RPE digests the photoreceptor tips and recycles their molecular components and the role of lipid and prostaglandin metabolism in that process.